Abrasion and F-Iron

[DoctaDajman]

If one were to get access to the surge of abrasion and F-Iron how well could the filling and tapping of the metal minds effect the speed with which you could be skating around?   With next to no friction to slow or hold you down would changing your mass be able to slow you or speed you up on its own?  

 

I know some funky mixing of worlds but just had the question pop into my mind as I was trying to figure out more about F-Iron.  

[Chiberty]

4 hours ago, Frustration said:

But it's not mass it's weight, the mass of the object retains the same mass.

And as such without any air resistence it would continue at the same speed.

F-iron changes mass, not weight. That's why Wax mentions that storing doesn't change his free-fall speed. Sazed is only able to fall like a feather because of air resistance.

But, the speed change Khriss asked Wax about is just a perception-influenced conservation of momentum. It doesn't have anything to do with friction. An abrasion user would speed up if they stored f-iron, and slow down if they tapped.

[Frustration]

if you were excpirencing no friction you shouldn't excpirience a change in speed

[Quantus]

Feruchemy is an internal thing, it affects how fast you can move your body.  Abrasion (so far as we've seen) is more like a field effect around the object that prevents friction in a way reminiscent of a mag-lev train.  

So, going by the tropes at least, Superspeed can work well with a low-friction skating style, but without the trained skill it can trip them up and be the reason speedsters tend to have so many Ice-based antagonists.  

[Frustration]

3 minutes ago, Quantus said:

So, going by the tropes at least, Superspeed can work well with a low-friction skating style, but without the trained skill it can trip them up and be the reason speedsters tend to have so many Ice-based antagonists.  

Wait that's the reason?!

I feel like I've been blind my whole life, I...

.........

[Quantus]

9 minutes ago, Frustration said:

Wait that's the reason?!

I feel like I've been blind my whole life, I...

.........

[DoctaDajman]

With the storage of weight specifically it is said that if you cut back weight you speedup but if you ramp up weight you would slow down.  (Many posts from the physics whizzes which is definately not me).   

So would the frictionless state ruin that change in speed that would come from shifting weight?  I imagine that you would definately have to work on getting used to the balance issues.  

 

Thanks for the answers so far.  

[HSuperLee]

2 hours ago, DoctaDajman said:

With the storage of weight specifically it is said that if you cut back weight you speedup but if you ramp up weight you would slow down.  (Many posts from the physics whizzes which is definately not me).   

So would the frictionless state ruin that change in speed that would come from shifting weight?  I imagine that you would definately have to work on getting used to the balance issues.  

 

Thanks for the answers so far.  

The friction-less state would not affect the odd speed up slow down effect created by changing weight (technically mass) while moving. We actually use that shifting effect as part of moving things around in space, as when two crafts dock together they both slow down and if they undock they both speed up due to the conversation of momentum, which requires no friction.

[Frustration]

12 minutes ago, HSuperLee said:

The friction-less state would not affect the odd speed up slow down effect created by changing weight (technically mass) while moving. We actually use that shifting effect as part of moving things around in space, as when two crafts dock together they both slow down and if they undock they both speed up due to the conversation of momentum, which requires no friction.

But it's not mass it's weight, the mass of the object retains the same mass.

And as such without any air resistence it would continue at the same speed.

[Dunkum]

I guess my first question would be is it actually a fully frictionless state when using abrasion?  or just mostly frictionless?  in the latter case, there should still be some effect, since friction is proportional to weight, but it might be hard to notice if most of the friction is gone. (i.e. the difference between 1% and .5% is hard to measure)

the reverse also works though - if you increase weight while increasing friction, it should make you harder to move overall.  since those 2 terms multiply together in the friction equation.

[DoctaDajman]

44 minutes ago, Chiberty said:

F-iron changes mass, not weight. That's why Wax mentions that storing doesn't change his free-fall speed. Sazed is only able to fall like a feather because of air resistance.

But, the speed change Khriss asked Wax about is just a perception-influenced conservation of momentum. It doesn't have anything to do with friction. An abrasion user would speed up if they stored f-iron, and slow down if they tapped.

I feel like this is two different answers.  My brain hurts after reading all the physics talk this morning on other iron feruchemy discussions.  

So storing makes you speed up as you get lighter, and tapping and getting bigger makes you slow down?  Or is there no difference?  

If abrasion such as in "Edgedancer" allowed lift to lower so much friction that she couldn't feel the wind on her face even as she was moving would storing and tapping still make a difference?   Or is the point that F-Iron won't change your momentum at all.  

Here are a couple of links to the threads that peaked my question.  

There is a ton of back and forth in these that I found a lot of fun to read.  I just dont have the mind to work any of it out.  

Does air resistance and friction make any difference in the speed of a fall or not?   I was always of the opinion that sazed floated like a feather super light.  Is that because he started at a very light weight?  The physics would support that making himself lighter mid fall would only speed up his decent and it is getting much heavier that would actually slow a fall.   Which sort of destroys the juggernaut charge the door then fill a bunch of weight and break free.   This would almost suggest that if you tap too much iron you would stop your forward progress completely.   

It has been a long long week.  I just feel like iron feruchemy is sailing over my head as far as when to store and when to tap.  Like I have thought about it backwards for years and years.   I was on team tin for ferrings and just recently tried to understand more uses of iron.  

[Chiberty]

2 hours ago, DoctaDajman said:

I feel like this is two different answers.  My brain hurts after reading all the physics talk this morning on other iron feruchemy discussions.  

So storing makes you speed up as you get lighter, and tapping and getting bigger makes you slow down?  Or is there no difference?  

If abrasion such as in "Edgedancer" allowed lift to lower so much friction that she couldn't feel the wind on her face even as she was moving would storing and tapping still make a difference?   Or is the point that F-Iron won't change your momentum at all.  

Here are a couple of links to the threads that peaked my question.  

There is a ton of back and forth in these that I found a lot of fun to read.  I just dont have the mind to work any of it out.  

Does air resistance and friction make any difference in the speed of a fall or not?   I was always of the opinion that sazed floated like a feather super light.  Is that because he started at a very light weight?  The physics would support that making himself lighter mid fall would only speed up his decent and it is getting much heavier that would actually slow a fall.   Which sort of destroys the juggernaut charge the door then fill a bunch of weight and break free.   This would almost suggest that if you tap too much iron you would stop your forward progress completely.   

It has been a long long week.  I just feel like iron feruchemy is sailing over my head as far as when to store and when to tap.  Like I have thought about it backwards for years and years.   I was on team tin for ferrings and just recently tried to understand more uses of iron.  

Yeah, that was two different answers. The first paragraph was my reply to Frustration, and the second was more just an answer to OP.

So for the first question, yes. You speed up when storing and slow down when tapping. For the second question, even with no friction or air resistance, f-iron affects your speed. That's because it conserves your momentum relative to... whatever the perceived reference frame is - usually the ground. So a if person taps iron while moving, their mass increases, so their speed goes down. It's like running into a bunch of stuff that's sitting still. 

Air resistance does affect how fast things fall. The higher the air resistance, the lower terminal velocity is. Sazed was floating like feather. If Sazed changed his mass midair to be really light... that's similar to getting recoil. Yes, the recoil pushes you forwards (down in this case) initially, but if it also makes you lose mass, your terminal velocity lowers, and that slows you back down.

[DoctaDajman]

2 minutes ago, Chiberty said:

Yeah, that was two different answers. The first paragraph was my reply to Frustration, and the second was more just an answer to OP.

So for the first question, yes. You speed up when storing and slow down when tapping. For the second question, even with no friction or air resistance, f-iron affects your speed. That's because it conserves your momentum relative to... whatever the perceived reference frame is - usually the ground. So a if person taps iron while moving, their mass increases, so their speed goes down. It's like running into a bunch of stuff that's sitting still. 

Air resistance does affect how fast things fall. The higher the air resistance, the lower terminal velocity is. Sazed was floating like feather. If Sazed changed his mass midair to be really light... that's similar to getting recoil. Yes, the recoil pushes you forwards (down in this case) initially, but if it also makes you lose mass, your terminal velocity lowers, and that slows you back down.

Okay.  I think that helps make more sense of it.  So those changes are still subject to any wind resistance would slow you even after an initial burst of speed in a fall assuming you have the space for it to work (opening a parachute just a hundred feet of the ground doesn't offer much help).  Assuming you could use abrasion and make yourself slick enough to ignore that same wind resistance I assume that initial burst of speed would just take significantly longer to taper off.  

This said when falling and trying to pad your fall is it better to increase mass greatly right before hitting the ground or store everything you can while still a few stories up?   Wax says that increasing his weight makes his body able to support that weight by default.  Would him drawing out and becoming a couple thousand lbs for the split second before hitting the ground slow him enough to not shatter every bone in his body from the fall?   

[Frustration]

4 hours ago, Chiberty said:

F-iron changes mass, not weight. That's why Wax mentions that storing doesn't change his free-fall speed. Sazed is only able to fall like a feather because of air resistance.

But, the speed change Khriss asked Wax about is just a perception-influenced conservation of momentum. It doesn't have anything to do with friction. An abrasion user would speed up if they stored f-iron, and slow down if they tapped.

actually no it isn't mass

you will notice that Wax doesn't gain increadible punching power, nor bullet resistence.

It's a change in the spiritual value that holds his weight not any physical change to him.

[Chiberty]

8 hours ago, Frustration said:

actually no it isn't mass

you will notice that Wax doesn't gain increadible punching power, nor bullet resistence.

It's a change in the spiritual value that holds his weight not any physical change to him.

It is explicitly pointed out in the books to be mass. Once when Wax says it doesn't change free-fall speed, and again when Khriss talks about conservation off momentum. Neither of those would be true if it was changing weight without changing mass. As for things like why he doesn't get bullet resistance, there are multiple theories for why, the one that I like being that the mass change doesn't affect the interactions between things internal to the user, so when a bullet enters them, it isn't affected.

[Frustration]

Just now, Chiberty said:

It is explicitly pointed out in the books to be mass. Once when Wax says it doesn't change free-fall speed, and again when Khriss talks about conservation off momentum. Neither of those would be true if it was changing weight without changing mass. As for things like why he doesn't get bullet resistance, there are multiple theories for why, the one that I like being that the mass change doesn't affect the interactions between things internal to the user, so when a bullet enters them, it isn't affected.

Wax says it doesn't change mass,

thoug looking through WoB's it seems that's how Brandon looks at it.

 

[Chiberty]

6 hours ago, Frustration said:

Wax says it doesn't change mass,

thoug looking through WoB's it seems that's how Brandon looks at it.

 

Wax never says that - in the scene you are thinking of, he says that it doesn't change density,  which does imply a constant mass, but Wax is simply incorrect in that scene. As shown by Wax's talk with Khriss, he has never even heard of conservation of momentum, so he is not a reliable source for physics-related info. In that scene, he refers to how he does not not become bullet resistant to claim he doesn't change density. With only that information, a constant mass would be a valid explanation. However, like I showed in my post you quoted, other information invalidates it, so some other explanation must be the true one (such as the mass change not affecting things internal to the user).

Here is Brandon's explanation:

Spoiler

Brandon Sanderson

Chapter Six

The fight in the ballroom

From the early days of the Mistborn books, I'd been planning how an Allomantic gunfight would go down. I felt it the next evolution in what has been stylistically a big part of these books.

There is a fine line to walk in a lot of these sequences. I've made something of a name for myself in the fantasy world by attempting to mix some scientific reasoning with my magic systems. At the same time, Allomancy was designed precisely with action sequences in mind. I wanted them to be powerful and cinematic—and a cinematic fight sequence is often at odds with realism. (Watch two people who really know what they're doing fight with swords sometime, then watch any fight sequence in a film. Most of the time, the film sequences stray far from what would really happen.)

So, as I said, I walk a line. Sometimes, there are things I just can't do because they violate what I've set up as the rules of the world. Other times, I design the setting and nature of the fight specifically to allow for certain types of cinematic sequences. One thing I like a lot about Wax’s abilities is the power he has to manipulate his weight. There's some realism to what he does—for example, increasing his weight doesn't make him fall more quickly, but it allows him to do some powerful things while falling. Destroying the chandeliers is an example.

At the same time, I acknowledge that the weight manipulation aspect of Feruchemy is one of its more baffling powers, scientifically. Is he changing his mass? If so, he should become more dense, which I don't actually make the case when it plays out in fights. (Otherwise, increasing his weight enough would make him impervious to bullets.) So, if it's not mass manipulation, is it gravity manipulation, like Szeth and Kaladin do? Well, again, not really—as when his weight increases, his strength and ability to uphold that weight increase as well. Beyond that, Wax can't make himself so light that he has no weight at all.

So . . . well, at this point, the ability to explain it scientifically breaks down. I do like what it does, but I have to set its boundaries and stick to them—and accept that some of what's going on is irrational. (And don't get me started on what should really be happening scientifically when Wayne speeds up time.)

Footnote: Brandon has stated that iron Feruchemy works by manipulating the Higgs field.
The Alloy of Law Annotations (March 14, 2014)

Essentially, he doesn't have an explanation. So any explanation we come up with that fits all the evidence could very well be true. But, simply saying it changes weight without changing mass does not fit all of the evidence, so it can't be true.

Edited June 4, 2021 by Chiberty

[DoctaDajman]

All the discussion is much appreciated.  Thanks all. 

In this thought... human battering ram.   Would charging a door and then tapping a bunch of iron actually give you the ability to break down the door or... from a physics standpoint is it more likely to make yourself heavier and then run at the door.   

Does the physical bonus of strength that comes from tapping iron (to cause you to be able to support the weight and move normally) allow a full sprint to continue as a full sprint no matter how much you store or tap iron and no matter what time you do it?   I envision the free falling to be a spot where it is just your weight vs air resistance.   But in a sprint your own effort driving you forward is going to be changed as you tap or store iron at a rate that is proportional to the weight you tap or store.  

Does tapping and storing effect your trajectory and velocity more when flinging yourself into the air than when using your body alone to propel yourself forward?  

[HSuperLee]

17 hours ago, DoctaDajman said:

All the discussion is much appreciated.  Thanks all. 

In this thought... human battering ram.   Would charging a door and then tapping a bunch of iron actually give you the ability to break down the door or... from a physics standpoint is it more likely to make yourself heavier and then run at the door.   

Does the physical bonus of strength that comes from tapping iron (to cause you to be able to support the weight and move normally) allow a full sprint to continue as a full sprint no matter how much you store or tap iron and no matter what time you do it?   I envision the free falling to be a spot where it is just your weight vs air resistance.   But in a sprint your own effort driving you forward is going to be changed as you tap or store iron at a rate that is proportional to the weight you tap or store.  

Does tapping and storing effect your trajectory and velocity more when flinging yourself into the air than when using your body alone to propel yourself forward?  

See, if iron-feruchemy was in any way consistent with how it messes with physics, that would be easier to answer. Unfortunately, its really not. Since we know momentum is conserved, you'd actually lose energy by tapping just before you hit the door, as you'd slow down quite a bit when you tapped. Theoretically if tapping gives you the strength to move your tapped weight around as if it was your normal weight Wax really should have super strength while tapping, which we know he doesn't, but it does at least mean you should be able to sprint normally. In which case, charging at the door while tapping, lets say up to twice your normal weight, you should have twice the normal energy, and thus that would be the better option. But at the same time, the lack of an increase in durability means rather than crashing through it, your more likely to just splat against it. As for the last question, kind of. The main reason it would have more of an effect in the air is because there's no way for a normal person to apply force in the air that would help them maintain a constant speed like you could on the ground. Crashers kind of throw that off because they can push off metal while still in the air, which makes it more similar to them to being on the ground.